1. Field of the Invention
The present invention relates to a cage with a lubricant storage space.
2. Discussion of the Background
Sealed roller bearings are generally lubricated with a lubricant that partially fills a free space between rotating elements. The quantity of lubricant available in the free space has a direct influence on the life of the roller bearing, however, overfilling the free space can result in heating of the roller bearing and in leaks.
Certain operating conditions provide an environment where the life of the roller bearing is limited by insufficient lubrication and not by the physical stresses that the rotating elements must tolerate. Under such conditions, the number of rotating elements in the roller bearing may be reduced in order to increase the quantity of lubricant in the roller bearing without increasing the percentage of fill. In certain operating conditions of the roller bearing, for example in a depressurized environment that tends to vaporize the usual lubricants, the quantity of lubricant nevertheless remains a limiting factor for the life of the roller bearing.
One way in which to extend the life of roller bearings is to use special, high-performance, slowly consumed lubricants and ceramic balls with a very low friction coefficient. However, special lubricants are very expensive.
In order to reduce the use of these types of lubricants, document JP 61 140616proposes the even distribution in the roller bearing of a more traditional lubricant stored beforehand in a roller bearing cage. JP 61 140616 describes a cage that forms a bridge including a chamber that contains the lubricant between two successive elements. The chamber communicates with a space in which the rotating elements move via a single narrow opening oriented from the accommodating space toward the bearing race borne by the outer ring of the roller bearing.
In the invention described in JP 61 140616, when the rotating elements rotate, the lubricant is expulsed progressively, under the effect of centrifugal force, from the chamber toward the bearing race borne by the outer ring. When the rotating elements roll along the bearing race, the rotating elements disperse the lubricant between the two roller bearing rings.
As the reserve lubricant of the invention described in JP 61 140616 does not increase the fill level, it does not lead to heating of the roller bearing. Its even distribution nevertheless makes it possible to increase the use life of the roller bearing. However, this type of cage is complicated to produce. A traditional molding process does not allow the creation of a virtually closed chamber. The cage must therefore be produced using two assembled parts. Likewise, a molding operation cannot allow the production of an orifice in the chamber. Additionally, the distribution of the lubricant generates negative pressure inside the chamber, which negatively impacts the even distribution of the lubricant.